import { useState, useEffect, useCallback } from 'react';
import {
  Stack,
  Title,
  Tabs,
  Group,
  Button,
  TextInput,
  Textarea,
  ActionIcon,
  Modal,
  Text,
  Select,
  Paper,
  Loader,
  Center,
  Alert,
} from '@mantine/core';
import { useForm } from '@mantine/form';
import { useDisclosure } from '@mantine/hooks';
import { IconEdit, IconTrash, IconPlus, IconBriefcase, IconMap, IconCertificate, IconInfoCircle } from '@tabler/icons-react';
import { useTranslation } from 'react-i18next';
import {
  notify,
  useErrorHandler,
  AdvancedTable,
  useServerTable,
  type AdvancedColumn,
} from '@ema-platform/ui';
import { LocationPage } from '../../location/pages/LocationPage';
import { CertificationPage } from '../../certification/pages/CertificationPage';
import {
  useGetOrganizationsQuery,
  useGetProfessionsQuery,
  useCreateProfessionMutation,
  useUpdateProfessionMutation,
  useDeleteProfessionMutation,
} from '../api/configuration-api';
import type { Profession } from '../types/configuration';

interface ProfFormValues {
  nameEn: string;
  nameAm: string;
  descEn: string;
  descAm: string;
  departmentId: string;
}

interface ProfFormProps {
  editingProf: Profession | null;
  deptOptions: { value: string; label: string }[];
  isSubmitting: boolean;
  onSubmit: (values: ProfFormValues, isEdit: boolean) => void;
  onCancel: () => void;
}

function ProfessionForm({ editingProf, deptOptions, isSubmitting, onSubmit, onCancel }: ProfFormProps) {
  const { t } = useTranslation();
  const form = useForm<ProfFormValues>({
    initialValues: { nameEn: '', nameAm: '', descEn: '', descAm: '', departmentId: '' },
    validate: {
      nameEn: (v) => (!v ? t('configuration.validation.nameEnRequired') : null),
      nameAm: (v) => (!v ? t('configuration.validation.nameAmRequired') : null),
      departmentId: (v) => (!v ? t('configuration.validation.departmentRequired') : null),
    },
  });

  useEffect(() => {
    if (editingProf) {
      form.setValues({
        nameEn: editingProf.name.en,
        nameAm: editingProf.name.am,
        descEn: editingProf.description.en ?? '',
        descAm: editingProf.description.am ?? '',
        departmentId: editingProf.departmentId,
      });
    }
  }, [editingProf]);

  const handleSubmit = form.onSubmit((values) => onSubmit(values, !!editingProf));

  return (
    <Paper p="md" withBorder mb="md" radius="md">
      <form onSubmit={handleSubmit}>
        <Stack gap="sm">
          <TextInput
            label={t('configuration.nameEn')}
            placeholder="English name"
            {...form.getInputProps('nameEn')}
            size="sm"
          />
          <TextInput
            label={t('configuration.nameAm')}
            placeholder="የአማርኛ ስም"
            {...form.getInputProps('nameAm')}
            size="sm"
          />
          <Textarea
            label={t('configuration.descEn')}
            placeholder="English description"
            {...form.getInputProps('descEn')}
            size="sm"
            autosize
            minRows={2}
          />
          <Textarea
            label={t('configuration.descAm')}
            placeholder="የአማርኛ መግለጫ"
            {...form.getInputProps('descAm')}
            size="sm"
            autosize
            minRows={2}
          />
          <Select
            label={t('configuration.department')}
            placeholder={t('configuration.selectDepartment')}
            data={deptOptions}
            {...form.getInputProps('departmentId')}
            size="sm"
            searchable
          />
          <Group justify="flex-end">
            <Button variant="default" onClick={onCancel} size="sm">
              {t('configuration.cancel')}
            </Button>
            <Button type="submit" size="sm" loading={isSubmitting}>
              {editingProf ? t('configuration.update') : t('configuration.create')}
            </Button>
          </Group>
        </Stack>
      </form>
    </Paper>
  );
}

function ProfessionTab() {
  const { t, i18n } = useTranslation();
  const locale = i18n.language as 'en' | 'am';
  const { handleError } = useErrorHandler();
  const { data: deptRes } = useGetOrganizationsQuery();
  const { pageIndex, setPageIndex, q, setQ, skip, take } = useServerTable({ pageSize: 10 });
  const {
    data: profRes,
    isLoading,
    isFetching,
    isError,
    refetch,
  } = useGetProfessionsQuery({ skip, take, q: q || undefined });
  const [createProfession, { isLoading: isCreating }] = useCreateProfessionMutation();
  const [updateProfession, { isLoading: isUpdating }] = useUpdateProfessionMutation();
  const [deleteProfession] = useDeleteProfessionMutation();

  const departments = Array.isArray(deptRes) ? deptRes : (deptRes?.items ?? []);
  // Server now paginates, so the previous client-side `isActive` filter is
  // dropped (it would hide rows outside just this page). Restore it via a
  // server-side `q` filter once the backend field name is confirmed.
  const professions = profRes?.items ?? [];
  const totalCount = profRes?.total ?? profRes?.count ?? professions.length;

  const [editingProf, setEditingProf] = useState<Profession | null>(null);
  const [showProfForm, setShowProfForm] = useState(false);
  const [deleteTarget, setDeleteTarget] = useState<Profession | null>(null);
  const [deleteOpened, { open: openDelete, close: closeDelete }] = useDisclosure(false);

  const deptOptions = departments.filter((d) => d?.status?.toLowerCase() === 'active').map((d) => ({
    value: d.id,
    label: d.name?.[locale] ?? d.name ?? '',
  }));

  const resetProfForm = useCallback(() => {
    setEditingProf(null);
    setShowProfForm(false);
  }, []);

  const handleEditProf = useCallback((prof: Profession) => {
    setEditingProf(prof);
    setShowProfForm(true);
  }, []);

  const handleDeleteProf = useCallback((prof: Profession) => {
    setDeleteTarget(prof);
    openDelete();
  }, [openDelete]);

  const confirmDeleteProf = useCallback(async () => {
    if (!deleteTarget) return;
    try {
      await deleteProfession(deleteTarget.id).unwrap();
      notify.success(t('configuration.deleted'));
      closeDelete();
      setDeleteTarget(null);
    } catch (e) {
      handleError(e);
    }
  }, [deleteTarget, deleteProfession, closeDelete, handleError]);

  const handleProfSubmit = useCallback(async (values: ProfFormValues) => {
    const name = { en: values.nameEn, am: values.nameAm };
    const description = { en: values.descEn, am: values.descAm };

    try {
      if (editingProf) {
        await updateProfession({
          id: editingProf.id,
          name,
          description,
          departmentId: values.departmentId,
        }).unwrap();
        notify.success(t('configuration.updated'));
      } else {
        await createProfession({
          departmentId: values.departmentId,
          name,
          description,
        }).unwrap();
        notify.success(t('configuration.created'));
      }
      resetProfForm();
    } catch (e) {
      handleError(e);
    }
  }, [editingProf, createProfession, updateProfession, resetProfForm, handleError]);

  const getDeptName = useCallback((deptId: string) => {
    const dept = departments.find((d) => d.id === deptId);
    return dept ? (dept.name?.[locale] ?? dept.name?.en ?? '-') : '-';
  }, [departments, locale]);

  const professionColumns: AdvancedColumn<Profession>[] = [
    {
      header: t('configuration.name'),
      cell: ({ row }) => row.original.name[locale],
    },
    {
      header: t('configuration.description'),
      cell: ({ row }) => (
        <Text size="sm" lineClamp={2} maw={200}>{row.original.description[locale]}</Text>
      ),
    },
    {
      header: t('configuration.department'),
      cell: ({ row }) => getDeptName(row.original.departmentId),
    },
    {
      header: '',
      size: 90,
      cell: ({ row }) => (
        <Group gap="xs">
          <ActionIcon variant="subtle" color="blue" size="sm" onClick={() => handleEditProf(row.original)}>
            <IconEdit size={14} />
          </ActionIcon>
          <ActionIcon variant="subtle" color="red" size="sm" onClick={() => handleDeleteProf(row.original)}>
            <IconTrash size={14} />
          </ActionIcon>
        </Group>
      ),
    },
  ];

  if (isLoading) {
    return <Center py="xl"><Loader /></Center>;
  }

  if (isError) {
    return <Alert icon={<IconInfoCircle size={16} />} color="red" title={t('configuration.error')} />;
  }

  return (
    <>
      <Group justify="space-between" align="flex-end" mb="md">
        <Title order={2}>{t('configuration.professionsList')}</Title>
        {!showProfForm && (
          <Button
            variant="light"
            leftSection={<IconPlus size={16} />}
            onClick={() => setShowProfForm(true)}
            size="sm"
          >
            {t('configuration.addProfession')}
          </Button>
        )}
      </Group>

      {showProfForm && (
        <ProfessionForm
          editingProf={editingProf}
          deptOptions={deptOptions}
          isSubmitting={isCreating || isUpdating}
          onSubmit={handleProfSubmit}
          onCancel={resetProfForm}
        />
      )}

      <AdvancedTable
        columns={professionColumns}
        data={professions}
        tableName={t('configuration.professionsList')}
        itemCount={totalCount}
        pageIndex={pageIndex}
        onPageChange={setPageIndex}
        pageSize={10}
        refresh={refetch}
        onSearchChange={setQ}
        isLoading={isFetching}
        emptyText={t('configuration.noProfessions')}
      />

      <Modal opened={deleteOpened} onClose={closeDelete} title={t('configuration.confirmDelete')} size="sm">
        <Text mb="md">
          {t('configuration.deleteConfirmText', { name: deleteTarget?.name?.[locale] ?? '' })}
        </Text>
        <Group justify="flex-end">
          <Button variant="default" onClick={closeDelete} size="sm">{t('configuration.cancel')}</Button>
          <Button color="red" onClick={confirmDeleteProf} size="sm">{t('configuration.delete')}</Button>
        </Group>
      </Modal>
    </>
  );
}

export function ConfigurationPage() {
  const { t } = useTranslation();

  return (
    <Stack gap="lg">
      <Title order={2}>{t('configuration.title')}</Title>

      <Tabs defaultValue="professions">
        <Tabs.List>
          <Tabs.Tab value="professions" leftSection={<IconBriefcase size={16} />}>
            {t('configuration.professions')}
          </Tabs.Tab>
          <Tabs.Tab value="locations" leftSection={<IconMap size={16} />}>
            {t('location.title')}
          </Tabs.Tab>
          <Tabs.Tab value="certifications" leftSection={<IconCertificate size={16} />}>
            {t('certification.title')}
          </Tabs.Tab>
        </Tabs.List>

        <Tabs.Panel value="professions" pt="md">
          <ProfessionTab />
        </Tabs.Panel>

        <Tabs.Panel value="locations" pt="md">
          <LocationPage />
        </Tabs.Panel>

        <Tabs.Panel value="certifications" pt="md">
          <CertificationPage />
        </Tabs.Panel>
      </Tabs>
    </Stack>
  );
}